Internal combustion engine



ct. 6, 1931. E. 5 HALL INTERNAL COMBUSTION ENGINE Filed Sept. 8. 1927 2Sheets-Sheet 1 Inventor 7 54; F W

Get. 6, 1931. s, HALL 1,825,691

INTERNAL COMBUSTION ENGINE Filed Sept. 8, 1927 2 Sheets-Sheet 2 g F" Ng4 v v Fig, 6

= Inventor Patented Oct. 6; 1931 UNITED STATES PATENT OFFICE EDWINSYDNEY HALL, OF NEW HAVEN, CONNECTICUT INTERNAL COMBUSTION ENGINEApplication filed September 8, 1927. Serial No. 218,223.

' m for any purpose, the construction disclosed herein being peculiarlyadvantageous when applied'to those engines used for such variable loadservice as that required of an automobile or a locomotive power plant. 5I More specifically, the chief objects ofmy invention are to provide inan internal combustion engine, the following novel features: Means forgoverning the power output, not only by throttling, but by controllingthe length of piston stroke in a manner making it possible to changereadily to any len th of stroke between and including zero an a suitablemaximum; means whereby the compression ratio may be kept constantirrespective of the length of piston stroke, or

Varied as a suitable function of stroke length, whichever may be mostdesirable;-

and means whereby the compression ratio may be easily adjusted to anyvalue between 33 desirablelimits, while the engine is running.

To one who is familiar with the theory' and practice of internalcombustion engines,

numerous advantages of an engine incorporating my invention will beapparent from the foregoing objects, as noted in the followingdescription, accompanying drawings,

and appended claims. In the drawings:

4b Figure 1 is a longitudinal section.

a study of the practical accomplishment of to in the followingdiscussion concerning the manner in which the compression ratio iscontrolled.

Figure 6 is a diagrammatic view of the swash plate and conoidal cam, inperspec-" tive, the position being that corresponding to zero pistonstroke.

Figure 7 is a longitudinal section of apistonand yoke assembly ofsomewhat different detail from that shown in Figure 1. i

In the following description, referring to the particular embodiment ofmy invention shown'in the drawings, the following notation is used: I

Reference numerals 1 to 9, inclusive, refer to reciprocating parts;

Reference numerals 10 to 19, inclusive, refer to stationary parts; and aReference numerals 20 to 33, inclusive refer to rotating parts, some ofwhich also have some axial movement.

Referring to the drawings, cylinders 11 in cylinder block 12 aredisposed about the main shaft 20 with their axe equidistant and parallelthereto. Each vpiston 1 is adapted to reciprocate in its respectivecylinder 11 and is operably connected to the rim of swash plate 23 bymeans of connect-. ing rod 3 (which may be integral with piston 1), yoke4 and 'adjoined parts, as follows: v

Yoke 4 is constrained to move only in linear motion parallel to the axisof cylinder 1'1, being shdably mounted on two guide studs 10 which mayalso help to hold the cylinder block 12 and crankcase 13 together. Thetwo branches of yoke 4 are disposed one on either side of the rim ofswash plate 23, and each branch bears one of a pair of thrust shoes 5having plane faces I separated from the swashplate rim only by. a filmof oil. J

The backs of thrust shoes 5 are formed as portions of the surface of thesame sphere, and are mounted in spherical sockets 6 and 7, so thatthrust shoes 5 may be self aligning with respect to the swash plate rim;In Figure ,3 several thrust shoes 5 are showri in plan View. swash plate23- moves, with respect to thrust shoes 5, in the direction in- 106.

dicated by the arrow. This is the well known Kingsbury thrust bearingconstruction which provides a wedge of oil on which the shoe ma ride.Each thrust shoe 5 may have a ten ency to turn out of line; thistendency is checked by the interlocking character of the tongue andslotted extensions on thrust shoes 5, as shown.

Referring again to Figure 1, socket 6 is fitted into a cylindrical seatof fixed depth in yoke 4; socket 7 is set in a cylindrical hole in theopposite branch of yoke 4 and abuts directly against the flanged end ofconnecting rod 3, the surfaces of the connecting rod flange being alsospherical and con centric with the spherical surfaces of thrust shoes 5.I

The outer spherical surface of the flange of connecting rod 3 isconstrained by the corresponding surface of nut 8, (split to permitassembling), which screws into yoke and is locked in place by bindingbolt 9.

This construction serves two useful purposes, namely: wear in the entireconnecting rod assembly may readily be taken up by' loosening bolt 9,screwing nut 8 into yoke 4 a sufficient distance, and then relockingwith bolt 9; the flexibility of the manner of connectmg yoke 4 toconnecting rod 3 helps to revent the piston from cramping in thecylinder, which might otherwise occur if the guide studs 10 shouldbecome worn or sli htly out of alignment.

igure 7 shows a simpler construction of the yoke assembly lacking thislatter feature. Here the connecting rod 3 is screwed directly into yoke4, and rigidly locked by Bolt 9. This would be a cheaper construcion.

Swash-plate 23 is pivoted on a pair of pins, com rising essentially atransverse or cross sha t 22, whose axis is perpendicular to the axis ofthe main shaft 20. The pins comprising cross shaft 22 are carried inbosses on sleeve 21 which is internally spllned to shaft 20 in a mannerto permit axial but not rotative movement between sleeve 21 and shaft20. Sleeve 21 can rotate in the journal bearing 15 and projects thru itinto hydraulic cylinder 14. Sleeve 21 carries a hydraulic piston 24 adated to be operated in hydraulic cylinder 14 y differential oil pressurefurnished thru ports 16 and 17 by suitable pumping equipment which maybe located in the space 18.

The hydraulic piston 24 and cylinder 14 may thus be the means by whichthe axial position of the cross shaft 22 may be varied. Mechanical orother means instead of hydraulic, could be provided without de partingfrom the scope of my invention.

When axial movement of the cross shaft 22 occurs, the arm 33, which is apart of swash plate 23, rides along a contour of cam 30. In practice,the arm 33 is provided with a suitable bearing shoe, omitted here forthe sake of clearness. The interaction of arm 33 and cam contour 30gives to swash plate 23 a predetermined slant from the normal position,for every axial position of cross shaft 22 along main shaft 20.

Cam 30 is mounted in a bearing 19 adapted to take both radial and thrustloads, and in a manner providing some axial adjustment of cam 30 withrespect to crankcase 13.

Main shaft 20 passes thru cam 30 and is connected thereto by a multiplethread in such a way that axial movement of the shaft 20, produced by anoutside force operating as on the shift collar 25 may rotate cam 30 withrespect to the shaft 20 an amount not necessarily more than onerevolution, for the purpose of bringing various other cam contours intocontiguity with arm 33 thus altering the angle of swash plate 23. Notethat except while making thisadjustment, shaft 20, sleeve 21, crossshaft 22, plate 23, and cam 30, all rotate together at the same angularvelocity.

Shaft 20 at its rearward end is also splined into the hollowtransmission shaft 31, which is centered preferably not by shaft 20 butby the collar 32 which is, in effect, a part of cam 30.

Figure 5 shows a kinematic sketch of my invention, wherein the mechanismis shown with an even number of cylinders. Ordinarily in a four strokecycle engine of this general type, an odd number of cylinders is used inorder to get a satisfactory firing order. An even number is preferable,however, for the sake of dynamic balance, and a suitable firing ordermay be had by using twice an odd number of cylinders. Also for thepurpose of explaining the kinematics of my invention, an even number ofcylinders is preferable as shown in Figure 5, where 8=1ength of stroke,proportional to the piston displacement in one cylinder;

v=1ength of clearance volume, proportional to the clearance volume;

h=radius of the "cylinder circle" thru which pass all the axes ofcylinders 11;

R=compresslon ratio;

a=a radius dependent on R, (a is the ordinate of the (ppipzti l which isfixed for-any constant value c and k are'constant lengths which locatethe end of arm 33 with respect to swash plate 23.

The compression ratio, R 7

according to customary usage.

s a a b By similar triangles, T :Fh

Therefore, R ill d a h R 1 from which a hR 1.

a is thus a function of the compression ratio R.

For a constant value of R, a will be constant and the curve of the camcontour is given by the parametric equawhere is the anglie of tilt ofthe swash plate from its position normal to shaft 20.

Figure 6 shows diagrammatically the swash plate 23 in position normal toshaft 20 corresponding to zero piston stroke. This view shows also theconoidal shape of cam 30, which it assumes when it is shaped to tions,

yield a constant compression ratio for any given setting relative toshaft 20, and at the same time, a continuous adjustment of compressionratio between limits, by movement relative to shaft 20. In this case,each contour of cam 30, (a contour being defined as the' intersection ofa plane thru the axis shaft 20, or in other words maintain a fixed angleof swash plate 23 relative to shaft 20, in which case, axial movement ofthe swash plate would change only the compression ratio,-leavin thepiston stro'ke constant.

j Again, wit the variable stroke, one com p'ressiom ratio may be allthat is desired. Then cam 30 would have but one contour, and it would,be unnecessary to provide means for rotatingor otherwise moving cam 30on shaft 20. Or means might be easily provided for moving this onecontour relative to shaft 20 to adjust the compression ratio, in casesome ad ustment were desirable. Further several contours may be combinedon a cam of shape similar to a polygonal pyramid, the various contoursbeing brought into use one at a time b means similar to thdsedescribed'herein. e ideal case indicated in Figure 6 results when thenumber of surfaces on such a polygonal cam is allowed to approachinfinity.

The cam contours shown in Figures 5 and 6 are actually plotted for theideal compression ratios noted, in a mechanism proportioned to the scaleof the drawings. Simi-- larly, the upper contour in Figure 1 would yielda compression ratio of 3, and the lower, a compression ratio of 5. A camof this sort, cooperating with axial movement of the swash plate, isobviously a very flexible melans of fitting this type of engine with analmost limitless assortment. of compression ratios.

V For ideal efiiciency, in operation, the pow; er output of an engineembodying my invention would be controlled by varying the piston strokeby changin the axial position of cross shaft 22, either by the hydraulicmeans'indicated, or by other suitable means, The throttle on thecarburetor would normally be carried wide open, thus avoiding allthrottling losses, but means should be provided to automatically closethe throttle more or less while decreasing the length of piston stroke.I vIt may be preferable to use manual control on the throttle in theusual way, adjusting the piston displacement necessary to produce therequired power, by a lever in lieu of the usual gear shift lever. Ifenough maximum piston displacement is provided, no transmission would beneeded except for reversing, since the equivalent. of a continuouslyvariable transmission is inherent in p the engine mechanism itself.

The ability to adjust the compression ratio, independently of pistonstroke length,

while the engine is running, not'only is significant in regard toeconomy and the possibility it offers of using a supercharger formaximum torque while at the same time maintaining high efficiency atreduced load, but it is a valuable feature for ice also.

' While I have shown specific structures for the purpose ofillustratlngmy invention, it is understood that I do not limit myself tothem alone, but include also structures which are substantially.equivalent to those described herein.

I claim:

airplane serva} ios 1. In an internal combustion engine, a

rotatable shaft, cylinders disposed about said shaft and having theiraxes parallel thereto, a swash plate rotatable with said shaft andmounted thereon, pistons reciprocatory in said cylinders and operablyconnected to aid swash plate, and means for varying the length of strokeof said pistons while maintaining their compression ratio in saidcylinders substantially constant. I

2. In an internal combustion engine, a rotatable shaft, cylindersdisposed about said shaft and having their axes parallel thereto, aswash plate rotatable with said shaft and mounted thereon, pistonsreciprocatory in said cylinders and operably connected to said swashplate, and means for varying the length of stroke of said pistons whilemaintaining their compression ratio in said cylinders substantiallyconstant, said means comprising essentially: means for moving said swashplate axially with respect to said cylinders, projecting means on saidswash plate,and a cam en'ga gedthereby and having a contourapproximating that mathematically necessary for constant compression.

3. In an internal combustion engine, a rotatable shaft, cylindersdisposed about said shaft'and having their axes arallel thereto, a swashplate mounted on said shaft, pistons reciprocatory in said cylinders andoperably connected to said swash plate, a cam associated with saidshaft, means for moving said swash plate axially with respect to saidcylinders, means 011 said swash plate engaging said cam and cooperatingwith said axial movement to control the tilt of said swash plate, andmeans for adjusting said cam relative to said shaft.

4. In mechanism of the sort described, the combination with a swashplate having a variable angular tilt relative to its axis of rotation,of a reciprocatory member comprising a pair of sockets formed asportions of the same spherical surface, a pair of thrust shoes seatedtherein and engaging opposite sides of said swash plate, a piston, andconnecting means between said pistonand said sockets.

5. In mechanism of the sort described, the combination with a swashplate, of a reciprocatory member operably connected thereto,

guide members'on which said reciprocatory member is slidable, a pair ofsockets formed as portions of the same spherical surface and borne bsaid reciprocatory member one on either si e of said swash plate, andlubricated thrust shoes seated in said sockets and having substantiallyplane faces engaging opposite sides of said swash plate. V

6. In mechanism of thelsort described, a rotating swash plate,lubricated thrust shoes arranged in pairs on either side thereof andmaintained in ali nment by tongue and slot\ extensions with tfiecorresponding shoes of adjacent pairs.

7 In mechanism of the sort described, the combination with a swash'platehaving a variable angular tilt relative to its axis of rotation, of areciprocating member comprising a pair of soc ets formed as portions ofthe-same-spherical surface, a pair of thrust shoes seated therein andengaging opposite sides of said swash plate, a iston having a flangedpiston rod, said flange having spherical surfaces concentric with saidsockets, and adjustable means for connecting said flange to one of saidsockets.

,8. The combination with a swash plate, of a reciprocating memberassociated therewith, including a'pair ofthrust shoes havingplane facesarranged in lubricated apposition on opposite sides of said swash plateand having back surfaces which are portions of substantially the samespherical surface, spherically shaped seats for said thrust shoes, apiston rod having a flange with spherical surfaces, an adjusting memberarranged to adjustably connect said flange with one of said seats andadjustably maintain one of said seat members in relation to the other.

9. In mechanism of the sort described, the

combination with a swash plate of a reciprocating member comprising apair of sockets formed as portions of t e same spherical surface, a andengagin op osite sides of said swash plate in lubricate apposition, apiston, connecting means between said piston and said sockets, andadjusting means wherewith to adjust the working clearances of saidcombination.

10. In, an internal combustion engine, a shaft, cylinders having theiraxes parallel tosaid shaft, pistons in said c linders a swash plate onsaid shaft an rotatable therewith, operative connections between saidpistons and said swash plate, means for varying the compression ratio insaid cylinders and means forvarying the stroke of the pistons whilemaintaining the compression ratio in the cylinders constant.

EDWIN SYDNEY HALL.

air of thrust shoes seated therein

